With the poor integration in Linux, ports of games just using a DirectX to OpenGL wrapper, and planned capability of Steamboxen using Windows if the user or manufacturer wants...there's no point to any of this.Let Valve do what Valve do best indeed. :-\

This is simply the repo to provide the client for Ubuntu, nothing more nothing less. They could very well have chosen something different for their own distro, which would make sense for several reasons.